Lymphatic System

Question 1

What are the functions of the lymphatic system? (3)

Answer 1

1. Fluid recovery (for excess interstitial fluid), filtration and drainage of infection and cellular decomposition.
2. Immune system
3. Lipid Absorption - has lacteals which absorb dietary lipids.

Question 2

What are the 4 components of Lymphatic system? (4)

Answer 2

1. Lymph
2. Lymph Vessels
3. Lymph nodes and organs
4. Lymphocytes

Question 3

What is lymph? (1)

Answer 3

Excess interstitial fluid that enters lymphatic vessels.

Question 4

How does interstitial fluid exchange in differ at arterial end of blood vessel compared to venous end of blood vessel in relation to lymph vessels? (2)

Answer 4

1. At arterial end, hydrostatic pressure pushes out fluid into interstitial space, which is taken up by lymph vessels.
2. At venous end, pressure falls so fluid starts to enter vein, excess fluid and proteins still taken up by lymph vessels.

Question 5

What happens when lymph vessels do not cope with accumulation of fluid? (1)

Answer 5

Oedema

Question 6

What are 5 mechanisms of lymph flow? (5)

Answer 6

1. Filtration pressure in tissue spaces
2. Contraction of neighbouring skeletal muscles
3. Respiratory movements
4. Contraction of lymphatic vessel walls
5. Valves preventing back flow in veins.

Question 7

What is the cycle of movement of lymph starting from interstitial space back to blood capillaries? (6)

Answer 7

Afferent: Interstitial space -> Lymphatic Plexuses -> Lymphatic vessels -> Lymph node

Efferent: Lymph node -> Lymphatic vessels -> Lymphatic trunks -> lymphatic duct -> Venous Circulation -> Blood capillaries

Question 8

Describe Lymphatic Plexuses (3)

Answer 8

1. Network of lymphatic capillaries with are tethered to surrounding tissue.
2. They originate blindly in extra cellular spaces and have blind ends.
3. Their endothelium have valve like flaps and no basement membrane

Question 9

What are Lacteals? What is Chyle?

Answer 9

It is a type of lymph vessel in small intestine which absorbs lipid and lipid soluble vitamins (including interstitial fluid).

Chyle is the milky fluid containing fat droplets which are drowned by lacteals.

Question 10

What is Lacteal? (2)

What is chyle? (1)

Answer 10

Lacteal is a type of lymph vessel found in villi of the small intestine. It has extra function of absorbing lipids and lipid soluble vitamins.

Chyle is the milky fluid containing fat droplets which are drowned by lacteals.

Question 11

Describe the structure of Lymphatic Vessels in comparison to veins (2)

Answer 11

1. Endothelium, tunica intima and tunica adventitia (thinner than veins)
2. A lot more valves than veins

Question 12

What are the differences between Superficial and Deep Lymphatic vessels? (4)

Answer 12

Superficial lymph vessels:

1. More numerous than veins, converge towards and follows venous drainage.
2. Drain into Deep Lymphatic vessels

Deep Lymph Vessels:

1. Accompany arteries
2. Receive drainage of internal organs

Question 13

What are the Lymphatic Trunks and where are they located? (5)

Answer 13

They are collecting vessels that receive lymph from lymph vessels.

Jugular Trunk (L&R) 
Subclavian Trunk (L&R) 
Bronchomediastinal Trunk (L&R) 
Lumbar Trunk (L&R) 
Intestinal Trunk

Question 14

What are the two lymphatic ducts and what parts of the body do they drain? (4)

Answer 14

1. Right Lymphatic duct - Drains upper right quadrant. Drains into Right jugular and right subclavian veins.
2. Thoracic duct - Drains rest of body. It has Cysternic Chyli (collecting sac) which merges lower lymphatic trunks from lower half of body

Question 15

Describe the Thoracic Duct (3)

Answer 15

Largest Lymph vessel, originated from Cysterna Chyli.

It ascends through aortic Hiatus in the diaphragm and sits in the posterior mediastinum.

Question 16

What are the primary lymphatic organs and what are the secondary lymphatic organs? (5)

Answer 16

Primary: Bone Marrow and Thymus

Secondary: Lymph Nodes, Aggregation of lymphatic nodules and Spleen.

Question 17

Describe the components of Bone Marrow (3)

Describe components of Thymus (2)

Answer 17

Bone Marrow: Red Marrow and Yellow Marrow.

• Red marrow has active hemopoietic stem cells stored in Spongy bone (medulla cavity in Children).
• Yellow Marrow is composed of adipose cells in compact area.
• Has specialised blood vessels called sinusoids which help release new blood cells and platelets.

Thymus: Fully formed at birth, shrinks with age. It has an outer cortex and inner medulla where T cells mature.

Question 18

Describe the Lymph Node:

1. What are the 3 supporting tissue
2. Describe flow of lymph from Afferent to efferent
3. Where are B cells and macrophages stored compared fo T-cells

Answer 18

1. Composed of Capsule, Trabeculae and Reticular (or medulla) tissue (contains Dendritic cells and macrophages)
2. Lymph flow: Afferent Blood vessel -> subcapular sinus -> Trabecular sinus -> Medullary Sinus -> Efferent blood vessel.
3. B cells and macrophages stored in Superficial cortex, T cells stored in Deep (paracortex)

Question 19

Give an example of superficial lymph node and example of deep lymph node (2)

Answer 19

Superficial: Right inguinal Lymph node

Deep: Normally in viscera (lungs, trachea) and abdomen. E.g Pulmonary lymph node in lungs

Question 20

What are the 2 forms of lymphatic nodules? (4)

Answer 20

1. Diffuse Lymphoid tissue: Associated with gut (GALT), Genitourinary tract/mucosa (MALT) and Resp system (BALT). Site for immune response - proliferation of B cells and development of lymph nodules.
2. Lymphatic Nodules: Dense mass of lymphocytes and macrophages which are permanent or develop in response to infection. Permanent e.g Peyer’s Patch in Small intestine.

Question 21

Describe the Spleen: Components (2) and Functions (3)

Answer 21

Largest Lymphoid organ, located in abdominal cavity. It has a white pulp (lymphatic tissue) and red pulp (red blood and immune cells)

Functions:

• Blood Filtration
• Recycling Iron and removing dead Red blood cells.
• Immune reaction to blood borne antigens